This proposal will use clinical, anatomic, endocrine, histopathologic and epidemiologic methods to gain information that will substantiate the hypothesis that potentially prolactin-secreting adenomas of the pituitary may exist in as many as 5% of women, that they may be a frequent cause of ovulatory dysfunction and infertility, and that their growth and clinical expression may be stimulated by estrogen use, usually in the form of oral contraceptives. An autopsy study will seek to determine the prevalence of prolactin-secreting adenomas by immunocytochemical and electronmicroscopic methods. A case-control study will ascertain whether oral contraceptive use and menstrual dysfunction are in fact more frequent in women with amenorrhea and hyperprolactinemia. A prospective study of oral contraceptive users will determine what proportion of women will develop frank hyperprolactinemia. The prolactin responses to a short course of estrogen administration will be assessed in women with ovulatory dysfunction and/or infertility who have basal serum prolactin concentrations in the high normal range and in a control group. This is an attempt to elaborate on the pathogenesis of pituitary adenomas and hyperprolactinemia and to design a method that will identify early those individuals who may harbor a nascent prolactin-secreting adenoma and who may be subject to estrogen-induced hyperprolactinemia.